Support configuring polymorphism in JsonbConfig

When you define your classes in different jar you can't specify every possible child / subtype via annotation on the superclass.

Please allow specifing the subtype mapping inside the JsonbConfig.

Start by reviewing JsonbConfig and the existing polymorphism annotations and subtype-mapping behavior in the Jakarta JSON Binding API. Determine how subtype mappings should be represented and applied when classes are distributed across different JARs. Done means the API supports configuring those mappings through JsonbConfig, with corresponding tests documenting the behavior.

Written by the indexing model from the issue text.